Alicyclic compounds having bridgeheads as appear in an adamantane skeleton are structurally rigid and have high heat resistance and excellent optical properties; and hence these compounds are used as highly functional resin materials, as intermediates for pharmaceuticals and agrochemicals, or as optical materials including photoresist materials (see, e.g., Patent Documents 1 to 3). Among them, hydroxy adamantane carboxylic acid compounds having both hydroxyl and carboxyl groups in the same molecule are advantageous in that they can be modified to have various functional groups by means of the difference in reactivity between hydroxyl and carboxyl groups, and therefore can be used as monomers for improving the performance of photoresists or as intermediates for pharmaceuticals and agrochemicals.
Several routes are known for synthesis of hydroxy adamantane carboxylic acid compounds. First, hydroxy adamantane carboxylic acid compounds are known to be generated as by-products in cases where adamantane carboxylic acid compounds are obtained from adamantanol derivatives or adamantanepolyol derivatives through the Koch reaction (see, e.g., Patent Document 4). However, there is a problem of low yield because hydroxy adamantane carboxylic acid compounds per se are not main target products and hence are difficult to isolate and purify. Moreover, there is disclosed a process for synthesis of hydroxy adamantane carboxylic acid compounds through oxygen oxidation reaction of adamantane carboxylic acid compounds, but this process has a problem in that the target compounds are difficult to isolate and purify because the reaction selectivity is low and the oxidation reaction proceeds at multiple positions to generate by-products (see, e.g., Patent Document 5). Further, there are also disclosed other processes, e.g., in which adamantane carboxylic acid compounds are halogenated and then substituted with hydroxyl groups (see Non-patent Document 1 and others), but these processes have problems in that the reaction should be conducted in two steps and thereby requires complicated and expensive operations and in that it is necessary to use halides which are high in environmental load.